PubMed · 13506700
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O C ACTIS. 1957-10-17. [Thyroid cyst].. https://pubmed.ncbi.nlm.nih.gov/13506700/
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Germline mutation of the folliculin gene (BHD) at chromosome 17p11.2 is associated with the development of multiplex hamartomas of the hair follicles, chromophobe renal cell carcinomas (RCC) and renal oncocytomas (RO). We have analyzed the folliculin gene with sequencing for mutations and the chromosome 17p11.2 with microsatellites for allelic changes in sporadic ROs and chromophobe RCCs. Allelic loss at chromosome 17 was seen in 8 of 8 chromophobe RCCs whereas none of the 8 RO showed alteration at this chromosomal region. Sequencing all exons from genomic DNA failed to disclose mutations of the folliculin gene in any of the tumors. We found a single nucleotide polymorphism (SNP) of G/A (nt 74) at the first exon in the untranslated region of the folliculin gene. We did not find a correlation between the SNP G/A or loss of the G allele and the expression level of either splice variants of the folliculin gene. Our data suggest the folliculin gene does not play a role in the tumorigenesis of sporadic chromophobe RCCs and renal oncocytomas.
Keratin immunohistochemistry represents a widely applied differential diagnostic tool in surgical pathology. To investigate the value of keratin subtyping for the diagnosis among histological subtypes of renal cell carcinoma and oncocytomas, we performed a detailed immunohistochemical study, applying 22 different monoclonal keratin antibodies on a large series of 233 renal tumors [125 conventional, 22 chromophobe, and 20 papillary (12 type-1, 8 type-2 tumors) cancers and 66 oncocytomas] using a tissue microarray technique. Immunoreactivity for keratin 7, 8, 18, and 19 was present in all tumor entities, albeit in varying quantities. With antibodies directed against keratins 8 and 18, oncocytomas showed a distinct perinuclear and punctate dot-like pattern, which was not observed in renal cancer specimens. The only tumors showing immunoreactivity for keratin 20 were two type-2 papillary cancers. All other monospecific keratin antibodies yielded consistently negative results. Overall, in contrast to some recent publications, keratin subtyping generally appeared to be of additional value only for the differentiation of renal epithelial tumors. Hence, with respect to differential diagnostic value, Hale's colloidal iron stain and vimentin immunostaining are still the most useful tools in renal tumor pathology.
Vascular endothelial growth factor (VEGF)-A is an important angiogenic factor in establishing the vasculature in renal cell carcinomas (RCCs). Since little is known about VEGF signalling in RCCs, the profile of phosphorylated KDR (pKDR) has been investigated and the intracellular location of the receptor has been examined in the present study. Using two monoclonal antibodies raised against the phosphorylated KDR epitopes (Y1059 and Y1214) known to mediate different VEGF functions, together with a commercial anti-KDR antibody and immunohistochemistry, the expression of pKDR was investigated in a series of normal (n = 25) and neoplastic kidneys (n = 54; clear cell n = 35; papillary n = 10; oncocytomas n = 8). pKDR was present in many tissue elements of both normal and neoplastic renal tissues, with strong expression in the cell membrane, cytoplasm, and nuclei of normal kidney and tumour cells, as well as endothelial cells in tumours of all histological types. Patterns and intensity were similar using both anti-pKDR antibodies. There was no significant correlation in clear cell carcinomas between pKDR expression and age (p = 0.57), tumour size (p = 0.2), gender (p = 0.59), grade (p = 0.2) or histological type (p = 0.36). To delineate further the intracellular processing that might account for the cellular distribution, confocal microscopy was also performed. Antibodies to the different phosphorylated epitopes demonstrated different intracellular staining patterns. This study shows that pKDR is present in a wide variety of renal tumours, suggesting that anti-VEGF therapy might have direct effects on tumour cells. It further suggests that cells traffic pKDR depending on the precise KDR tyrosines that are autophosphorylated in a manner that enables receptor activation to result in different functions.